1. Field of the Invention
The present invention relates to a diaphragm unit, a light intensity adjusting device, a lens barrel, and an imaging apparatus.
2. Description of the Related Art
Portable imaging apparatuses such as moving image cameras and digital still cameras or projection-based optical apparatuses such as liquid crystal projectors are provided with a light intensity adjusting device.
For example, the light intensity adjusting device includes a diaphragm unit adjusting the size of a diaphragm opening centered on an optical axis of an optical system and an ND filter unit reducing the light intensity passing through the diaphragm opening.
As such a type of diaphragm unit, a diaphragm unit is known which employs an iris diaphragm adjusting the size of the diaphragm opening by swinging plural diaphragm blades arranged around the diaphragm opening in cooperation (see JP-A-2004-333554 (Patent Document 1)).
As such a type of ND filter unit, an ND filter unit is known in which an ND filter is made to protrude to and to retreat from the diaphragm opening (see JP-A-2001-117133 (Patent Document 2)).